Math practice for 13 year olds - page 52 of 435
Number of problems found: 8682
- Groundwater
The groundwater for collecting rainwater has the shape of a prism with trapezoidal bases a=5 m, c=7 m, 4 meters apart. The depth of the tank is 3 meters. How many hectoliters of water can it hold at most if 8% of its volume is taken up by the pump and pip
- Similar triangles
We have similar triangles ABC with angle CAB=45° and angle ACB= 30° and a similar triangle OPN. What is the angle NOP in a similar triangle?
- 3 weights
A two-arm lever has a 0.5 kg weight on the left arm at a distance of 64 cm from the axis of rotation and a 0.8 kg weight at a distance of 30 cm from the axis of rotation. How far on the right arm must the 0.7 kg weight be placed for the lever to be in bal
- Tightened 83632
The key works like a lever, where one arm is the radius of the bolt, and the other is the length of the key. If key no. 12 (for screws with a diameter of 12 mm) and a length of 12 cm can be tightened with a maximum force of 100 N, what force does the wren
- Triangle and Cone
A right triangle has legs 3 cm and 4 cm long. One cone (let's call it A) was created by rotating this triangle around the long leg, and the other (let's call it B) by rotating it around the shorter leg. Which cone has: a) a larger volume b) a smaller surf
- Staircase - escalator
A moving staircase moves downwards at a speed of 0.6 m/s. The staircase makes an angle of 45° with the horizontal. A person weighing 80 kg walks upwards at a speed of 0.9 m/s. Determine the distance covered by the person and the work done by him before he
- Passenger car and truck
At 6 a.m., a truck left the Factory at 40 km/h. At 6:30, a car drove behind it at 70 km/h. How long, at what time, and how far from the Factory will the passenger car catch up with the truck?
- Dimensions 83603
The perimeter of the rectangle is 56 cm, and its length is three times greater than its width. What are the dimensions of the rectangle?
- Textbook 83602
A textbook with a workbook costs 14 euros. The workbook is 6 euros cheaper than the textbook. How much is the textbook, and how much is the workbook?
- A lottery
In a lottery, a person chooses four different natural numbers at random from 1 to 10, and if these four numbers match the four numbers already fixed by the lottery committee, he wins the prize. What is the probability of winning the prize in the game? (Th
- Representing 83587
Juraj paid 87 euros for ski training, representing 60% of the total. How much does ski training cost?
- Chocolate 83581
The candy store sold two types of chocolate candies. Red for 8 Sk and blue for 6 Sk. We bought 20 candies for 136 CZK. How many candies are blue and how many red? We have red candies: We have blue candies:
- Following bike
At 8:00 a.m., my son rode a bicycle at a speed of 18 km/h. at 8:20 a.m., his father followed him at a speed of 60 km/h. How long will it take for Dad to arrive?
- Purchase - owners
The house is divided between the owners in shares of 1/8, 1/12, 1/6, 1/8, 1/4, and 1/4. Except for one with a 1/4 share, they decide to sell their shares. How will he divide the purchase price of CZK 12960000?
- Different balls
We have four different boxes and three identical balls. Place the marbles in these boxes so that the boxes can contain one, two, three or none. How many other locations are there?
- Trajectory
Nelka holds a dumbbell in her hand at arm's length. Then she lifts it by bending her arm only at the elbow, making an angle of 135°. The exercise ends with the dumbbell lowering along the same path. What is the length of the trajectory the dumbbell follow
- Cauliflower: 83523
Miss Kapustová sold vegetables in the market. Yesterday, she offered two types of cauliflower: a large one for 25 CZK and a small one for 15 CZK. She sold 8 crates of 20 heads and earned a total of CZK 3,270. How many large and how many small cauliflowers
- Rectangular roof
Our house's roof is rectangular. When it rains, the water drains through the gutter. How much water flowed from our roof during a storm when we know that 12 liters of water fell on every 1 m² of surface? The roof width is 6m, the length is 9m, and the slo
- Isosceles weight
A designer weight is made from a glass cube by cutting a three-sided prism with an isosceles triangle base that is right-angled and whose arm is half the length of the cube edge. What percentage of the cube is cut off when making the weight?
- Children books
The library has 2748 books, three times more for adults than for children. Thus, the library has 2748 books for adults and 2748 books for children.
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